A bottle generally consists of a shoulder portion with an opening, a side wall or main body which is generally cylindrical in shape, and a bottom joining the side wall. Because of the tendency of the wall of the pressurized plastic bottle to creep under internal pressure, it is a general practice to orient the plastic material and to design the bottle shape in such a way to improve resistance against creep. For the bottom section, it is known that if a uniform material distribution is achieved, the stress caused by the internal pressure can be minimized by using an outwardly hemispherical configuration. Molecular orientation can be obtained by blowing a properly designed parison in a blow mold in the orientation temperature region to enhance the strength. The hemispherical configuration, requires a separate means of support to make the bottle stand upright. For this purpose, a base cup is normally used.
In the handling of pressurized fluid containers during filling and storage, an important consideration is the resistance of the container to top load and the rigidity of the container.
One type of base cup used commercially includes an annular support area adapted to engage the hemispherical portion of the bottle. The support area is spaced radially inwardly of the peripheral wall of the cup. Such a construction provides satisfactory support and stability under most conditions. It has also been suggested that a secondary support area may be provided by a re-entrant portion of the side wall of the cup, as shown in U.S. Pat. Nos. 3,927,782 and 4,187,276. However, this provided only an additional support since the wall is capable of axial deformation.
Where the container is to be utilized for carbonated beverages that are pasteurized, such as beer, the pasteurization is conducted at elevated temperatures and prolonged exposure to these temperatures may cause deformation of the plastic material. Accordingly, it is desirable to provide a configuration of the pressurized fluid package which will expose the greatest possible surface of the package directly to the pasteurization thereby minimizing the time and the resultant adverse effects of prolonged exposure to high temperatures.
Among the objectives of the present invention are to provide a pressurized fluid package which utilizes a container and a separate base wherein the package has resistance to top load and increased rigidity.
In accordance with the invention the pressurized fluid package comprises an oriented plastic container and a base. The oriented plastic container includes a cylindrical side wall, a neck, a neck finish on the upper end of the neck for receiving a closure, and a hemispherical bottom wall. The plastic base includes a seating area for engaging a surface on which the package is supported, and a peripheral wall extending upwardly and outwardly and terminating in an annular free edge portion defining an inner primary support area engaging a complementary area of the hemispherical wall of the container to provide primary and sole support axially for the container in the base. The base has a second contact area for receiving adhesive to bond the hemispherical bottom wall of the container.